[Christian Weichel] has been hard at work developing LogicAnalyzer, an open source tool that may interest you. It is designed with SUMP Logic Analyzers in mind but a main goal is expandability. What this means is that it plays nicely with things like the Open Workbench Logic Sniffer or you can do a bit of fiddling to get it to work with your own designs. The program is based on Eclipse so you should be familiar with how it works and you can get it running easily on multiple platforms. Take a look at the wiki for a quick start.